Stock-based Compensation - Stock Option (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2021
Maximum
Stock-based compensation expense
Expiration period	10 years
Stock options
Stock-based compensation expense
Options outstanding to purchase of common stock	1,837,540	1,837,540	2,193,915
Shares available for future issuance			575,782
Shares
Outstanding at the beginning of the year (in shares)	1,837,540
Options granted (in shares)	360,625
Options exercised (in shares)	(4,250)
Outstanding at the end of the year (in shares)	2,193,915	1,837,540
Exercisable at the end of the year (in shares)			1,286,093
Weighted average exercise price
Outstanding at the beginning of the year (in dollars per share)	$ 71.80
Options granted (in dollars per share)	117.46
Options exercised (in dollars per share)	112.42
Outstanding at the end of the year (in dollars per share)	$ 79.22	$ 71.80
Exercisable at the end of the year (in dollars per share)			$ 58.22
Additional disclosures
Proceeds resulting from exercise of stock options	$ 0.5	$ 0.0
Weighted-average grant date fair value of options (in dollars per share)	$ 85.17	$ 68.71